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Archived

Avalanche Forecast

Apr 22nd, 2023–Apr 23rd, 2023
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions:

Numerous very large deep persistent slab avalanches have been reported on a variety of aspects in the alpine.

Avoid steep, rocky, shallow, or thin-to-thick areas in the snowpack where triggering slabs is more likely.

Confidence

Low

Avalanche Summary

Numerous naturally triggered very large (up to size 3.5) deep persistent slab avalanches were reported on a variety of aspects in the alpine on Friday. They failed on either a crust/facet layer 100+cm deep or weak facets at the bottom of the snowpack. Follow the link on this MIN for the photos of these notable avalanches.

Observations are limited at this time of year, please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.

Snowpack Summary

A weak layer of crust/facets down 100+ cm and/or weak facets at the bottom of the snowpack have recently become reactive.

Warm temperatures and/or solar radiation will increase the likelihood of triggering very large avalanches.

Cornices are large and loom over slopes below like gargoyles.

Recent wind has varied in direction so watch for lingering wind slabs on all aspects at upper elevations.

Weather Summary

Saturday Night

Cloudy with isolated flurries; 0-3 cm / 20 km/h southeast ridgetop wind / Temperature at treeline around -3 C / Freezing level 700 m

Sunday

Mostly cloudy with isolated flurries; 5-10 cm / 30 km/h southeast ridgetop wind / Temperature at treeline around 0 C / Freezing level 1000 m

Monday

Mix of sun and cloud with flurries; 5-10 cm / 30 km/h south ridgetop wind / Temperature at treeline around -3 C / Freezing level 700 m

Tuesday

Mix of sun and cloud / 30 km/h south ridgetop wind / Temperature at treeline around -2 C / Freezing level 800 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Cornice failure may trigger large avalanches.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.

Avalanche Problems

Deep Persistent Slabs

A weak layer of crust/facets down 100+ cm and/or weak facets at the bottom of the snowpack have recently become reactive.

Warm temperatures and/or solar radiation will increase the likelihood of triggering very large avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3.5

Cornices

Cornices are very large and loom over slopes below like gargoyles. Cornice falls may trigger large avalanches on the slopes below.

Aspects: North, North East, East, North West.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1.5 - 2.5

Wind Slabs

Recent wind has varied in direction so watch for lingering wind slabs on all aspects at upper elevations.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2